1. Field of the Invention
The present invention relates to a medical system capable of processing an image captured with a medical image collection apparatus. More specifically, the present invention relates to a technique capable of associating a plurality of cross-sectional images with each other and generating corresponding cross-sectional images from different three-dimensional images.
2. Description of the Related Art
In the medical field physicians diagnose a site of lesion while reading a medical image of a target object displayed on a monitor. Tomographic images (i.e., three-dimensional images) of the inner state of target objects are widely used as medical images.
The medical image collection apparatus (i.e., the modality) capable of capturing tomographic images is, for example, an ultrasonic image diagnosis apparatus (ultrasonic apparatus), an Optical Coherence Tomography (OCT apparatus), a Magnetic Resonance Imaging apparatus (MRI apparatus), an X-ray Computed Tomography apparatus (X-ray CT apparatus), or a combination of like apparatuses.
For example, in the field of mammary gland imaging, the procedure of imaging diagnosis may include identifying a lesion position in a breast based on an image captured with an MRI apparatus and observing a state of the identified lesion with an ultrasonic apparatus.
In this case, an image capturing protocol in the mammary gland imaging department generally includes performing an imaging operation with the MRI apparatus in a state where a diagnosis target is held in a prone position and then performing an imaging operation with the ultrasonic apparatus in a state where the diagnosis target is held in a supine position.
In this case, considering a deformation of the breast occurring when the posture of the diagnosis target changes in the above described image capturing operations, a physician obtains an estimated position of the supine position lesion based on the position of the lesion identified based on the prone position MRI image. Then, the physician operates the ultrasonic apparatus to capture an image of the lesion at the estimated position of the lesion.
However, the deformation of a breast occurring due to a change in image-capturing posture is very large. Therefore, the position of a lesion in the supine position estimated by the physician may greatly differ from an actual lesion position. To solve this problem, it may be useful to use a conventional method for generating a virtual supine position MRI image that can be obtained by performing deformation processing on a prone position MRI image.
The position of a lesion in the virtual supine position MRI image can be calculated based on information relating to the deformation from the prone position to the supine position. Alternatively, the position of a lesion on an image can be directly obtained by reading the generated virtual supine position MRI image.
If the deformation processing is accurate enough, the actual lesion in the supine position will be present in the vicinity of the estimated lesion position on the virtual supine position MRI image.
Further, not only calculating the position of a lesion on the supine position MRI image that corresponds to the actual lesion position on the prone position MRI image but also displaying corresponding cross sections of the prone position MRI image and the supine position MRI image may be often required.
For example, the physician may want to precisely observe a state of the lesion on the original image. To this end, it is necessary to display a cross-sectional image of a non-deformed prone position MRI image that corresponds to a cross section including the lesion designated on a deformed virtual supine position MRI image.
In addition, the physician may want to confirm how across section of the non-deformed prone position MRI image changes to a cross section of the deformed virtual supine position MRI image.
Currently, there is a conventional method for displaying corresponding cross-sectional images taken from two three-dimensional images that are different from each other in deformation state. Japanese Patent Application Laid-Open No. 2008-073305 (hereafter “JP 2008-073305”) discloses an example of such a conventional method.
According to the method disclosed in JP 2008-073305, processing to be first executed is deforming a previous three-dimensional image so as to fit to a present three-dimensional image. Further, processing to be next executed is displaying a present cross-sectional image together with a previous cross-sectional image in such a manner that two images are arranged symmetrically in the right and left direction or symmetrically in the up and down direction.
In addition, Japanese Patent Application Laid-Open No. 2009-090120 (hereafter “JP 2009-090120”) discloses a method of displaying two image slices positioned on the same plane. Specifically, in the method disclosed in JP 2009-090120, an image slice is designated in one image data set to discriminate a corresponding image slice in the other image data set, so as to display the two image slices positioned on the same plane.
However, according to the method discussed in JP 2008-073305, segmented cross sections corresponding to each other are extracted after the previous three-dimensional image and the present three-dimensional image are deformed to have an identical shape. That is, processing time and resources are required to obtain deform the images and obtain the identical shape.
Therefore, the method discussed in JP 2008-073305 is unable to display corresponding cross-sectional images while maintaining differences in shape.
On the other hand, the method discussed in JP 2009-090120 merely suggests selecting image slices from respective image data sets. Therefore, in ordinary cases, the method discussed in JP 2009-090120 is unable to appropriately generate a corresponding cross-sectional image in the other image data set so as to correspond to a cross-sectional image designated in one image data set.